Method of and means for generating the involute profiles of gear teeth



Nov. 2 3 1926. v 1,608,052

J.-H. BARNES METHOD OF AND MEANS FOR GENERATING THE INVOLUTE PROFILES 0F GEAR TEETH Filed August 27, 1923 3 Sheets-Sheet 1 IN VEN TOR,

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Nov. 23 1926.

J. H. BARNES METHOD OF AND MEANS FOR GENERATING THE INVOLUTE PROFILES OF GEARTEETH Filed August 27, 1923 3 Sheets-Shes? 2 /@NVENTOR, W

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Nov. 23 1926. 1;60s,052 V J. H. BARNES METHOD OF AND MEANS FOR GENERATING THE INVOLUTE PROFILES OF GEAR TEETH Filed August 27, 1923 3 Sheets-Sheet 5 t z 0 N a g t v INVENTOI.-

7%; ATTORNEY involute.

Patented Nov. 23, 1926.

UNITED STATES PATENT OFFICE.

JAMES H. BKRNES, OF MONTGOMERY, NEAR DAYTON, OHIO.

METHOD OF AN D MEANS FOR GENEBATIN G THE INVOLUTE PROFILES OI TEETH.

Application filed August 27, 1928. Serial No; 659,564.

It is the principal object of my invention to provide a simple, accurate and economical method of, and means for, generating the profiles of the teeth of gears and similar elements after said teeth have been roughed out.

The means which I provide for generating the involuteworking surface or profiles of gear teeth and like elements, is a rolling curve shaving cutter whose cutting action is in the direction of the roll of the gear teeth as distinguished from other cutters of the rotary, rack, pinion and hob type whose cutting action is at right angles to the direction of the roll of the gear teeth. Gear teeth which are cut in the previously known manner, as by a rack why a hob, necessarily have minute ridges extending transversely across the workin surfaces of the gears, and as these ridgesro l andslide together when two or more of these gears are intermeshed. the result is a noise and an eXcessoffrition which: is overcome by shaping the teeth in the manner to be herein described in which the shave of the finishing cut is taken from the end of the tooth inwardly toward the root of the tooth or in the direction of the 7 In involute teeth the direction of the involute is the direction of roll of the teeth. The finishing cut is preferably made in a single operation by having the width of the eutter of substantially the sameextent as thefull width of the gear.

Among the advantages which I claim for my method of cutting gears is accuracy of product, speed of production, interchangeability and reduction of noise of operation of the gear that is cut.

Other important and incidental objects will be brought out in the following specification-and particularly set forth in the subjoined claims.

In the accompanying drawings illustrating my invention, Figure 1 is a diagrammatic view showing the generation of an involute line. Figure 2 is a diagrammatic view showing the generation of an involute surface. Figure 3 is a diagrammatic view showing how the generation of an involute surface is adapted to my method of generating the involute profiles of gear teeth. Figure 4 is a side elevational view of a device which may be employed for carrying my method of cutting gears into effect. Fig- For the purpose of quickly and accurately generating the involute profiles of spur gear teeth, I rferably employ a plane tool identical witii the generating lane illustrated in Figure, 3, forthe fol owing reasons.

If a taut string is wound varound a cylin-.

der and then unwound, the free end of the string will describe an involute line, and the string will always be tangent to the periphery of the cylinder. For example, m Figure 1 0 represents the cylinder, and p, p, and p designate successive positions of the free end of the taut string, describing the involute line i. t, represents the length of the string or tangent for the position 1),, and and t, for the position [2 Thus the involute line i is described by a point in a tangent identical with the string, rolling the periphery of the cylinder, the length of the tangent increasing as the unwinding proceeds.

In Fi ure 2, p and p and p and p are escribing points for involutes 'L and 1, I, and 1,, which connect p to p and p to p respectively, designate two positions of the line which generates the involute surface 8.

If, as in Figure 3, there is provided a tool m havin'ga cutting edge n that corresponds with the generating line Z, inFigure 2, in a plane 0 at approximately right angles to the rolling tangent t,, then the edge 91, in the tangent planet, is the generating line for the involute surface s.

A hand power device that operates on the above described principle for finishing the twist of the tool holder.

preferably consists of a casting having two bands 20, 20. Each pair of these bands is upright arms 2, 2 containing holes in their so secured to its respective wing portion, upper ends into which are pressed the renear the outer end thereof, that their oppoduced ends of two base cylinders 3, 3 corresite ends will be free for attachment to the sponding to the cylinder 0 in Figures 1, 2 periphery of the base cylinder so that said and 3. Each base cylinder 3 forms a bear wing portion may freely roll upon the lating for a sleeve which extends from the outter without sliding. Figs. 4 and 5 show the side surface of the upright member to the tool holder in a central position, while Figs. face of the roughed gear blank to be cut, 7 and 8 show the tool holder in positions the right sleeve, the roughed gear and the where the cut has not been started, and with left sleeve being designated by the numerals the blade advanced well into the cut respec- 4, 5 and 6 respectively. (See Figures 4 tively. This rolling or rocking movement and 7,) of the tool holder is effected by an oscillat- The inner end of the sleeve 6 is drilled ing bracket 21 of U section, having two arms and tapped to provide a hole 7 into which 22, 22 that are pivotally secured to reduced the inner threaded end of a spindle 8 is portio n s of the base cylinders 3, 3. Secured screwed after the latter has been passed between the upper portions of the arms .22, through the bore of the gear and the sleeve 22 of this bracket is a transverse shaft 23 4. (See Fi ure 7.) Placed on the outerend upon the middle portion of which there is of the spindle is a thrust washer 9 which is-loosely mounted between two collars 24, 2-1, forced against the outer end of the sleeve i a roller 25 which engages the top surface of by the hexagon head 10 of the spindle. 'the body portion of the tool holder 18. The

The sleeve 6 has an outer reduced end 11 roller 25 thus provides a roller means operwhich is drilled and tapped to receive 'a ably connected to the main support 1 to screw 12 which passes through a thrust exert a downward force on the tool holder washer 13 that engages the outer face of an so as to assist the bands 20 in taking the index wheel 14 keyed on the reduced end 11 strain which results when a cut is being of the sleeve, to press it firmly against the taken by the tool 27. Pressed into a 'hole shoulder face of the latter. (See Figure 7.) inthe ,top portion of the bracket 21 is a Near its outer edge the index wheel 14 conhandle 26 by means of which the bracket tains a series of radial holes 15 correspondis oscillated to impart a rolling motion to ing in number to the number of teeth on the the tool holder and to the tool now to be gear 5v to be cut. Provided in the left updescribed, which it carries. right member 2 below the axis of the gear 5, To receive thistool, which will be desigis a hole 16 to receive a removable index pin nated by the numeral 27, a recess is cut in 17 after the latter has been pacsed through the body portion of the tool holder, and in one of the radial holes 15 in the index wheel this recess the tool is firmly held by screws 14. (See Figures 7 and 8.) The sleeves 4 28, 28 which enter-tapped holes 29, 29 in and 6, which are mountedin the support 1, said body portion. (See Figures 4, 7 and together with the associated spindle 8, form 8.) The tool- 27 is thus held by the tool a means for holding a gear or a gear blank holder 18 in right relationship to the gear 5 in position, and the base members 3-3 form to be cut. master surfaces of curved contour about In operation, the oscillating bracket 21 which the tool holder is constrained to osis moved by its handle 26 to its initial cutcillate. v ting position on a tooth of the gear 5, which Adapted to rock or roll upon. the cylinis held stationary between the sleeves 1 and drical base members 3, 3 is a tool holder 18 6 when the latter sleeve is locked by the now to be described. The latter preferably index pin 17 by virtue of its passage through consists of a casting which hastwo side the radial hole 15 for that position in the wing portions that are integrallyconnected index wheel 14, into the locking hole 16 to a raised central body portion of U section in the base member 1. The gear now being to provide the necessary clearance for the locked in a stationary position. the bracket outer portion of the gear 5. (See Figure 21 is oscillated by its handle 26 to cause the 7.) The'body portion of the tool holder tool 27 to generate the involute working surhas two downwardly projecting thrust face or profileof one side of the tooth; flanges 19, 19 which engage the inner ends and when the position of the gear is reof the base cylinders 3, 3 to prevent any side versed, the involute profile of the other side of the tooth may be generated in the same To maintain at all times the proper coumanner. (See Figures 4 and 8.)

tact between the lower surfaces of the wing It will-now be seen that the movement of portions of the tool holder 18 and the pethe tool 17 by the oscillating bracket 21, in ripheries of the base cylinders 3. 3, the fol-. generating the involute profile of one side lowing means are provided. Secured in of a gear tooth, will exactly follow the parallelism to the under surface of each movement of the edge a in Figure 3 when wing portion of the tool holder,'is a pair of generating the involute surface 8. To the cylinder .0 in the latter figure, correspond e base cylinders 3, 3 on which roll the lower wing surfaces of the tool holder 18 that correspond to he tangents t, in said figure. The bands20 which'maintain the proper contact between those wing surfaces and the base cylinders, may be each likened to the taut string in' Figure 1. This comparison beinglestablished, it follows that my. method and means for generating the involute rofiles of gear teeth will result, among'otier things, i'naccuracy and speed of production as well as in the reduction of the noise of operation of the gears that are cut.

The device which I have described for cutting the gears may be modified if desired, and may be driven by any motive power other than that derived from the hand- Furthermore, while I have shown but one tool in thedevice illustrated in the drawings, these tools may be in multiple.

Having described my invention, I claim:

1. The herein described method of finishing the curved non-circular working surfaces of a rolling power transmitting body which consists in causing a tool to shave the working surfaces of the body so that a continuous out is taken for substantially the entire length of said working surface in the direction of roll of said surface.

2, The herein described method of finishing a curved working surface of the teeth of a toothed power transmitting body which consists in causing a tool to take a continuous shave on a working surface of the teeth in the direction of roll of the teeth.

3. The method of cutting an involute working surface on a blank which consists in'cutting the working surface so that a continuous cut of a substantial length is made in the direction of the involute to out every point in the working surface in the direction of the involute- 4. The method of finishing the curved working surfaces of gear teeth, which consists in causing a wedge shaped shaving tool to successively shave the working surfaces of the teeth so that continuous shaves are made of substantial lengths on each working surface in the direction of roll of the working surfazes.

5. The method of finishing a substantially involute working surface of a gear tooth which consists in shaving the working surface of the tooth from the end inwardly to the root of the tooth in a single cut.

6. The herein described. method of cutting the curved working surfaces of gear teeth which consists in shaving the working surfaces of said teeth so that continuous shaves are taken in the direction of rollof the teeth.

'7. The method of finishing an involute working surface of an involute spur ear which consists in causing a straight-e god shaving tool to shave the working surface so that a single continuous shave is taken from, the end inwardly to the root of a tooth.

8.'The method of involute gear teeth consisting in making a roughed gear blank and subsequently shaving the working surfaces of the teeth so that a single continuous shave is made for tl1e full length of each working surfacein the direction ,of roll of said surface.

9. A toothed member having ear teeth with power transmitting surfaces ished by a continuous shave for the full length of each surface, made inthe direction of roll of said surface'said surface being perfectly smooth along lines inthe direction of roll of said surface.

10. A member having an involute surface of a substantial length finished by a single continuous cut' madein the direction of the involute, every point in said surface being cut in thedirection of the involute. 11. A gear having involute working surfaces finished by shaving each surface by a single continuous shave made for the full length of said working surface from the end inwardly to the root of the. tooth said sur-.

making substantially substantially in the direction of roll of the surface by a single continuous shave.

14. A spur gear having gear teeth with substantially involute working surfaces which are perfectly smooth along substantially involute lines, finished by shaving each surface for the full width thereof by a single continuous shave made for the full length of said workingsurface from the end inwardly to the root of the tooth.

15. In a device of the class described, a support, means mounted in said support for holding a roughed blank to be provided with finished power transmitting surfaces, a tool holder mox'ably mounted adjacent to said blank. a tool therefor, and means for. moving said tool holder so that the tool takes a continuous shave on the blank sub stantially in the direction of roll of said surface. 1

16. In a device of the class described, a support, means mounted in said support for holding a gear fixed inposition while being c ut, a tool holder movably mounted on said means, a tool therefor, and means formoving saidtool holder so that the tool takes a tooth of said gear in the direction of roll of shave in the direction of roll of a tooth of said gear to cut a Working surface on said tooth.

17. In a device of the class described, in combination, a support, means mounted in said support for holding a gear, a tool holder movably mounted adjacent to said gear, an edged tool fixed in said holder, and means for moving said tool holder so that the edge of the tool moves along a substantially involute path so as to shave the working surfaces of the teeth from the ends inwardly to the roots thereof.

18. In a device of the class described, in combination, a support, means mounted in said support for holding a gear in fixed position while being cut, a tool holder 'movably mounted adjacent to said gear, a straight edged tool-of substantially the same width as the gear mounted in said tool holder, and

- means for moving said tool holder so that the straight edge of the tool describes an involute curved surface in space so as to shave a Working surface of the tooth from the end inwardly towards the root thereof in a single operation.

19. In a device of the class described, a support, means for holding a roughed gear in said support, means for indexing said gear, a tool holder movably mounted in said support, a tool fixed in,said tool holder, means for moving said tool. holder so that the tool takes a shave on a working surface of a tooth of said gear in the direction of roll of the tooth and a roller cooperating with said tool holder to take a'portion of the'strain on said holderwhen a shave is made and to transmit said strain to said support.

20. In a device of the class described, in combination, a support, means for holding a gear, a tool holder movably mounted adjacent to said gear. a straight edged tool removably mounted therein, means for oscillating said tool holder backand forth along a predetermined path so that every point in the edge of the tool travels along substantially involute paths to describe a substantially involute Working surface on said gear, and a roller cooperating With said tool holder to transmit a port-ion of the strain on said holder, when the shave is made to said support.

21. In a device of the class described, in combination, a support, means mounted in said support for holding a gear, a device for moving said means a predetermined amount for indexing said gear, a tool holder movably mounted on said means adjacent to said gear, a straight edged tool 'removabl held therein, aroller cooperating with said tool holder and said support for moving said tool holder so that the cutting edge of the tool shaves an involute Working surface on a the tooth, and means for operating said roller so as to oscillate the tool holder.

22. In a device of the class described, the combination with a support, of means for holding a gear in a stationary position to the latter. a tool holder oscillatably mounted on said support adjacent to said gear, a tool carried by said holder having a substantially straight cutting edge and mounted in fixed position in relation to said holder while a cut 'is being made, a cylinder, tension elements interconnecting said cylinder and said tool holder to restrain said tool holder to roll on the surface of said cylinmounted in said support, a tool holding means mounted on said support, a tool therefor, and mechanism for relatively moving said two means so that the tool takes a continuous shave on the working surface of a toothon said gear in the direction of roll of said surface and for the full length of said surface.

24. In a device of the 'classdescribed, in combination, a support, gear holding means mounted in said support, a tool holding means mounted on said support, a tool therefor, and mechanism for relatively mov ing said two means so that the tool takes a single continuous shave along a substantially involute path so as to continuously shave each working surface of the teeth from the ends inwardly to the roots thereof.

In a machine for cutting involute surfaces in the direction of roll of the involute, in combination, a support, blank holding means for holding a blank to be provided with an involute surface, a cutter, means for holding said cutter, a device for maintaining one of said means stationary on said support While a cut is being made on said blank, and mechanism for moving said other means on'said support so that said cutter cuts an involute surface on said blank of a substantial length, said cut being made in the direction of roll of the involute surface. 26. A machine for cutting involute surfaces in the direction of roll of the involute, comprising, in combination, a support, blank holding means on said support for stationarily holding a blank to be provided with an involute surface, a cutter, a cutter holding means movably mounted on said support, and means for moving said cutter holding means so. that said cutter moves along an involute path in space to cut an in volute surface of substantial extent on said blank so that the out is made in the direction of roll of the involute surface.

27. A machine for cutting involute surfaces in the direction of-roll of the mvolute, comprising, in combination, a support,

blank holding means on 'said support for stationarily holding a blank to be provided with an involute surface, a cutter, a cutter holding means movably mounted on said support, and means for moving sai cutter holding means so that said cutter moves along an involute path in space to cut an 28. In a gear cutting macl1ine,-in combina tion, a support, means for holding a roughed gear blank fixed in position on said support while a cut is being made, tool holding means oscillatably mounted adjacent to said gear, a straight edged shaving tool mounted in said tool holder and fixed therein while a cut is being made, a curved master surface fixed to said support, having a constant distance across the same, said master surface oscillatably supporting said tool holder thereon, means controlling the movement of said tool holder on said master surface to cause the edge of the tool to describe a substantially involute surface, and means for moving said tool holder to cause the edge of said tool to shave a substantially involute working surface on said gear blank so that each shave is continuous and made substantially in the direction of roll of said surface, and means for indexing said gear blank and gear blank holding means between cuts.

29. In a device of the class described,.in combination, a'support, means for holding a roughed gear in said support, a tool holding means mounted in said support ad'acent to said gear, a tool mounted in sai tool holding means having a wedge shaped operating edge of substantially the same width as said gear, a device for relatively indexing said two means, and mechanism for relatively moving said two means so that the tool takes a shave on the working surface on the tooth of said gear in the direction of roll of said surface.

30. In a deviceof the class described, in combination, a support, means mounted in said support for holding a roughed gear, tool holding means mounted in said support adjacent to said gear, a straight edged tool removably held in said tool holding means, a device for indexing said gear in relation to said tool holding means, and mechanism including a roller cooperating with one of said means and said support for relatively moving said two means so that the cutting edge of the tool takes a shave on the working surface of the tooth of said gear from the end inwardly to the root thereof.

31. In a device of the class described, in combination with a support, means for holding a roughed gear blank in said support,

tool holding means mounted in said support adapted to hold a tool, a cylinder, mechanism operably interconnecting said cylin-' der and said tool holding means so that they are constrained to relatively oscillate one on the other and comprising a roller oscillatable about the axis of the gear and interconnecting the tool holder and the support for governing the movements of the tool holder and transmitting strain on said tool holder to said support, means for producing such relative oscillation, the axes of the cylinder and ot the'gear blank being alined so that said tool cuts a working surface on the teeth of said gear blank in the direction of roll of said surface.

32. In a device of the class described, in combination with a support, means for holding a roughed gear blank in said support, tool holding means mounted in said support, a straight edged tool in said toolholding 'means, a cylinder, mechanism 0 erably interconnecting said cylinder an said tool holding means so that they are constrained to oscillate one on the other in conjugate relation, and means for producing such relative oscillation, the axes of the cylinder and of the gear blank being alined so'that said tool cuts an involute working surface on the teeth of said gear blank in the direction of roll of said surface.

33. 'In a device of the class described, in combination with a support, means for-holding a roughed gear blank in said support, tool holding means mounted in said support, a tool in said tool holding means, a curved master surface, mechanism operably interconnecting said master surface and said tool holding means'so that they are constrained to relatively oscillate one on the other and comprising a roller oscillatable about the axis of the gear and interconnecting the tool holder and the support for governing the movements of the tool holder and transmitting strain on said tool holder to said sup.- port, means for producing such relative oscillation, the axes of the master surface and of the gear blank being alined so that said tool cuts a working surface on the teeth of said gear blank in the direction of roll of said working surface,

.34. In a device of the class described, in combination, a support, means for holding a roughed gear blank in said support, tool holding means in said support, a wedge shaped tool in said tool holding means, a master surface having a curved contour and having an axis fixed in said support, mechanism operably interconnecting said master surface and said tool holding means so that they are constrained to oscillate one on the other, and means for producing such oscillation, theaxes of the master surface and of the gear blank being coincident so that said tool cuts a substantially involute working surface on the teeth of said gear blank in tgh'e direction of roll of the said working surace.

35. In a device of the class described, in combination, a support, means for holding a roughed gear blank in said support, tool holding means in said support, a straight edged tool in said tool holding means, a master surface having a generally curved contour fixed in said support, mechanism operably interconnecting said master surface and said toolholding means so that they are constrained to oscillate one on the other, and means for producing such oscillation,

said mechanism and said last named meansincluding a roller operably interconnected with said tool holding means, the-axes of.

the master-surface and of the gear blank being coincident so that the tool holding means is constrained to oscillate about said generally curved master surface in a curved path, so that said tool cuts a Working surface on the teeth of said gear blank in the direction of roll of the said working surface.

36. In a device of thetype described, the combination with a support, of means for holding a gear in a stationary position in the latter, a tool holder oscillatably mounted in'said support over the gear, a tool carried by said holder, a cylinder, taut elements wound thereon and means for moving said holder to cause the tool to engage the involute portion of a tooth of said gear in a surface generated by a line connecting the toward each other from the upper ends of said arms, a sleeve rotatable in each cylinder, a spindle passing through one sleeve into the other sleeve, a gear mounted on said spindle between the sleeves, a tool holder free to oscillate about the axes of the cylinders, bands connected at their opposite ends to the holder and cylinders so that said holder may freely roll on the latter and still be maintained in contact with them, a tool carried by said holder to engage the involute portion of a tooth of said gear, and means for oscillating the tool holder for the purpose specified.

38. In a device of the type described, the combination with a base support, -of a pair of base cylinders fixedly secured within said support, a sleeve rotatable in each cylinder, a spindle passing through one sleeve into the other-sleeve, a gear mounted on the spindle for tight engagement by the inner ends of said sleeves, a tool holder oscillatable over the peripheries of said cylinders above the gear, a tool carried by said holder. to engage the involute surface of the latter, indexing means secured to one of said sleeves to turn the gear to present successive teeth thereon to said tool, and means for locking the indexing means in a stationary position after a gear tooth has been brought into proper position for engagement by the tool.

In testimony whereof I have hereunto set my hand this 25th day of August, 1923.

JAMES H. BARNES. 

